This invention relates to connecting arrangements for exhaust gas systems in motor vehicles.
Since motor vehicle exhaust gas systems, and particularly the catalytic converter of an exhaust gas system, may become very hot in operation, a heat shield pate is usually mounted under the exhaust gas system or the catalytic converter to prevent, at least to a large extent, excessive application of heat to the roadway together with the consequent hazards. Because the exhaust gas system, and specifically the converter, may have a wide range of temperatures, a corresponding compensation of lengths between the exhaust gas system with the catalytic converter and the heat shield plate in the longitudinal direction of the vehicle must be permitted.
For this purpose, various connecting devices including sliding seats have been employed in the past in which one of the components, i.e. the heat shield plate or a component of the exhaust gas system, is connected to a slide which is displaceable with clearance in the longitudinal direction of the vehicle in a slide track part of the sliding seat. The other component is connected to a sliding seat housing forming a guide for the slide so that relative displaceability of the two components with respect to each other is maintained because of the displaceability of the slide within the sliding seat housing. A disadvantage of such arrangements of two components with a sliding seat, however, is that a sliding seat consisting of a housing, an inserted slide and a tightening screw is comparatively costly and expensive to produce. Furthermore, proper guidance of the slide in the guide throughout the high-temperature range to which the sliding seat is subjected is uncertain.
German Offenlengungsschrift No. 42 28 511 and U.S. Pat. No. 5,339,500 describe holding clamps for connecting plates having unlike expansion behaviors, in which two clamp legs are connected by a resilient intermediate portion and through holes are provided in the legs, through which a screw can be passed, so that the two clamp legs are pressed together toward stops against the resilient spring action of the intermediate portion. The clamp legs are each provided with anterior and posterior spring tabs having a spacing in their relaxed condition which is less than the thickness of the plate to be clamped. This holding clamp arrangement connects plates having different expansion behaviors, especially in automobile construction for fastening plastic housings or baffles to body parts. With a screw inserted in the clamp and tightened, the spring tabs engage the plates under some tension, and permit a relaxation in the thickness direction upon thinning of the plate resulting from the action of heat so that secure retention of the thinned plate continues to be possible. The clamping force of the spring tabs is selected so that lateral displacement of the clamped plate due to expansion is possible.
However, the configuration of the connecting arrangement according to U.S. Pat. No. 5,339,500 is not optimal. The threaded part of that arrangement is configured as an integral part of the connecting device, namely as part of a leg bent in a U-shape. Consequently, in the first place the bottom part of the connecting device requires more space and in the second place the connecting device cannot be adapted in use by the mechanic.